Combination catalytic reactor and exhaust silencer for internal combustion engines

ABSTRACT

A perforated horizontal partition extends all across a horizontally extended chamber, dividing it into an upper compartment filled with particulate catalytic material and a lower compartment across which extends a baffle tube into which engine exhaust is introduced. Pressurized air enters the lower compartment through a port near the baffle tube. Gas and air pass through perforations in all parts of the partition, up through the bed, the particles of which define numerous tortuous paths, and out through a horizontal row of ports at a level above the partition.

United States Patent 1 Allard et al.

[ Apr. 3, 1973 [54] DEVICE FOR SECURING A SOLID PROPELLANT GRAIN IN A COMBUSTION CHAMBER [75] Inventors: Pierre Allard, Atony; Jacques Laparre, Vfroflay; Claude Lemaitre, Wissous, all of France [73] Assignee: Societe National Industrielle Aerospatiale, Paris. France [22] Filed: May2l,l97l

[2i] Appl.No.:l45,834

[30] Foreign Application Priority Data May 28, 1970 France ..70l9637 [52] US. Cl ..60/255; 102/103 [51] Int. Cl ..F02k 9/04 [58] Field of SearLu-,u .;..-L-..U -m ....,....60/25 5, 60/3947; 102/103, 102,493,494, 102/495 49.6

[5 6] References Cited UNITED STATES PATENTS Alden ..60/Z55 Rush ..60/255 De Fries et al ..60/255 FOREIGN PATENTS OR APPLICATIONS 1/1947 France ..60/255 1,81 1.330

8/1970 Germany ..60/255 Primary Examiner- Al Lawrence Smith Assistant Examiner-- Michael Koczo, .l r. Attorney- Karl W. Flocko ABSTRACT A device for securing a propellant grain in the combustion chamber of a propellant 'unit comprises a plate fast with the front end of the propulsion unit. The front face of the propellant grain is fixed rigidly to the plate. The propellant grain is secured to the plate by means? stud inenfbe rs engaging int?) openings formed adjacent the periphery of the plate and permitting expansion of the grain without engendering significant stresses. A grid fast with the rear face of the grain and having a cylindrical bearing surface cooperates with a bore of the rear end'of the propulsion unit.

'5 Claims, 4 Drawing Figures DEVICE FOR SECURING A SOLID PROPE LLANT GRAIN IN A COMBUSTION CHAMBER The present invention relates to a method and device for securing a solid propellant grain in its combustion chamber.

Several techniques exist for securing a solid propellant grain inside a rocket combustion chamber in such manner as to allow the grain to withstand the mechanical and thermal stresses which may arise during transport, storage or operation.

One such technique consists in casting the solid propellant in the form of a grain in the combustion chamber and in causing the outer surface of the grain to adhere strongly to the rocket case, either partly or wholly. This casting-bonding technique cannot be applied in all cases however, and particularly not in the case of a solid grain by reason of the magnitude of the stresses developed by the temperature variations.

In another known technique, sometimes referred to as the free grain technique, thesolid propellant grain is restrained in the rocket combustion chamber by means of more or less elastic wedging devices in order to allow for thermal expansion and damp the mechanical loads to a sufficient degree to maintain the integrity of the propellant grain.

In accordance with this invention, the front face of the propellant grain is rigidly fixed to the front end of the combustion chamber, and the rear face of the grain is positively located yet allowed to slide in relation to the rear end of the combustion chamber, while at the same time retaining effective thermal protection of the lateral walls of the combustion chamber.

The subject device of this invention enables the propellant grain to expand or contract freely, whereby it is not subjected to large stresses notwithstanding the big difference between the coefficients of expansion of the grain and the chamber.

It further enables displacement of the propellan grain in relation to the chamber to be limited.

The description which follows with reference to the accompanying non-limitative exemplary drawing will give a clear understanding of how the invention can be carried into practice.

In the drawings:

FIG. 1 is a sectional view of a rocket chamber having a solid propellant grain fixed therein;

FIG. 2 depicts on an enlarged scale the portion of the device contained within frame A of FIG. 1;

FIG. 3 is a section taken through the line IIIIII of FIG. 1; and

F IG. 4 is a fragmental view in section through the line IV IV of FIG. 3.

Referring to the figures in the accompanying drawing, there is shown thereon a device according to this invention for securing a cylindrical solid propellant grain 1 contained in a combustion chamber 2 of a propulsion unit of the kind used, for instance, for propelling a tactical missile. It must be possible for such a propulsion unit to be stored handled and fired at any temperature between -40C and 50 C. If the diameter of the grain 1 is in the region of 033 metre and its length about 1.50 metre, then its length will vary by approximately 20.5 mm and its diameter by approximately 6mm between the aforesaid temperature limits.

The front face and lateral surface of the grain l is coated with an inhibiting varnish 7. In order to safety. A systematic diametrical clearance is provided I between the grain 1 and the wall of the combustion chamber in order to permit free expansion of the solid propellant grain responsively to temperature variations.

The front face of the grain 1 is fixed against a metal plate 3 made fast with the front end of the propulsion unit by a nut 6. Adjacent its centre, the plate 3 is formed with an annular ridge 5 adapted to engage into a matching recess in the grain 1, thereby locating the latter with respect to the plate.

The diameter of the ridge 5 is preferably comparatively small so that the mechanical stresses resulting from the different expansions of the metal and the grain should remain small.

Metal sectors or parts 4 are embedded in a circular groove formed in the front face of grain 1 and are restrained therein by inhibiting varnish which fills the groove. Studs 14 screwed into the sectors 4 secure propellant grain l to the plate 3, and the ends of studs 14 accordingly engage into openings 15 in plate 3 and are made fast thereinby nuts 16.

The major axes of the openings 15 extend radially with respect to plate 3 in order to permit unrestrained thermal expansion of the propellant grain in relation to the plate.

Alternatively, while the sectors 4 could be replaced by a continuous ring they are nevertheless to be preferred in order to facilitate securing of the grain and limit the thermal stresses.

A grid 12 made of refractory material and capable of withstanding the heat of the combustion gases is secured to the rear face of grain I by-studs 11.

Each stud 11 is formed with a shank the shape of which makes for easier restraining of the stud in the propellant grain through the use of a volume of inhibiting varnish 17 in the region of the grains periphery.

Thefree end of each stud 11 extends through the grid and receives a circlip 18 which keeps the grid in contact with the grain.

Since the coefficients of expansion of the grid and the propellant grain are different, the studs are allowed to shift laterally within a lodging l9 machined in the grid.

A ring 13 of elastomer material is positioned around each stud 11 and located in a bore formed in grid 12. Clearance is provided between ring 13 and solid propellant grain l, and the purpose of this ringis to damp movements of the solid propellant grain.

Grid 12 is formed with an annular locating member constituting a bearing surface 20 which enables it to be positively located in a matching guide member or bore 9 formed in the rear endpart 8 of the propulsion unit. The part 8 is made of the same material as the grid, whereby such positive location remains effective at all temperatures since the grid and the part 8 have the same coefficients of expansion.

Grid l2 slides over its locating means when the grain 1 becomes longer or shorter responsively to temperature changes. A longitudinal clearance is provided to permit expansion over the desired temperature range. Manifestly, the length of cylindrical portion 20 is calculated according to the variation in the length of the grain, in order to ensure that positive location remains effective even at the lowest design temperature.

It goes without saying that changes and substitutions of parts may be made in the preferred embodiment hereinbefore described without departing from the scope of the invention as set forth in the appended claims.

We claim:

1. A device for securing a solid propellant grain in a rocket motor chamber comprising:

a plate member secured to the front end of the rocket motor chamber and having openings embodied therein adjacent its periphery,

stud member means for rigidly securing the front face of the solid propellant grain to said plate member and extending through said plate member openings,

metal parts embedded in the solid propellant grain and comicteaio said stud member means, i

an annular locating member attached to the opposite end of the solid propellant grain,

means for fixing the rear face of the solid propellant grain to said annular member,

and ,a matching guide member for said annular locating member secured to the rear end of the rocket motor chamber.

2. A device as claimed in claim 1, further characterized by:

said plate member including a projecting annular portion thereon fitting to a matching circular recess in the front face of the solid propellant grain for positive location of the grain in relation to said plate member.

3. A device as claimed in claim 1, wherein said annular locating member is a grid comprising a cylindrical bearing surface, said matching guide member being formed by a bore of matching shape.

4. A device as claimed in claim 3, wherein said means for fixing the rear face of the solid propellant grain to said grid are stud members embedded in the solid propellant grain, a ring made of elastomer material being further interposed between each said stud member and said grid.

5. A device as claimed in claim 1, wherein the front face and the lateral surface of the solid propellant grain further include a coating of inhibiting varnish. 

1. A device for substantially diminishing both the noise level and the air pollutant content of exhaust gas issuing from an internal combustion engine, characterized by: A. means defining a horizontally elongated chamber having a bottom wall that is inclined upwardly from near one end thereof and having upright side and end walls and a substantially horizontal top wall; B. a perforated partition extending substantially horizontally across the chamber in spaced relation to its top and bottom walls to divide the chamber into an inlet compartment beneath the partition and an outlet compartment above it; C. said chamber having
 1. an exhaust gas inlet port in one of its side walls, near said one end of the chamber and at a level below the partition,
 2. a row of outlet ports that are spaced from one another along a horizontal line a substantial distance above the partition, and
 3. a port for pressurized air in another wall, at a level below the partition; D. a baffle tube in the inlet compartment, extending lengthwise from one to the other of the side walls of the chamber and into which the gas inlet port opens, said baffle tube having an imperforate wall portion at the side thereof that faces the partition and having perforations in its other wall portions so that exhaust gas entering the chamber is discharged from the baffle tube in directions that encourage it to flow uniformly through all of the perforations of the partition; and E. a bed of particulate catalytic materiAl substantially filling the outlet compartment, of a type having the property of promoting the chemical combination of oxygen and pollutioncausing products of incomplete combustion, the interstices between the catalytic particles providing a multitude of tortuous passages through which air and exhaust gas that have passed through the perforations of the partition must flow to reach said outlet ports, and in so doing become intimately mixed and chemically combined and acoustically muffled.
 2. The device of claim 1, further characterized by: F. said port for pressurized air being in the bottom wall of the chamber, beneath the baffle tube.
 2. a row of outlet ports that are spaced from one another along a horizontal line a substantial distance above the partition, and
 3. A device for substantially diminishing both the noise level and the air pollutant content of exhaust gas issuing from an internal combustion engine, characterized by: A. walls defining a chamber having substantial horizontal extent; B. a perforated partition extending substantially horizontally across said chamber to divide the same into an inlet compartment below the partition and an outlet compartment above it; C. a port in a wall of the chamber for admitting engine exhaust gas into the inlet compartment; D. a generally tubular baffle member into which said port opens and which extends substantially horizontally across the inlet compartment, spaced beneath the partition, the portion of the wall of said baffle member that faces the partition being imperforate, but other portions of said wall being apertured, whereby the exhaust gases entering the inlet compartment are encouraged to pass into the outlet compartment through perforations in all parts of the partition; E. means defining an inlet through which pressurized air can flow into the inlet compartment in a direction to promote its mixing therein with engine exhaust gas; F. the chamber having a plurality of outlets therein that are spaced from one another and spaced above said partition; and G. a bed of particulate catalytic material substantially filling said outlet compartment, of a type having the property of promoting the chemical combination of oxygen and pollution-causing products of incomplete combustion, the interstices between the catalytic particles providing a multitude of tortuous passages through which air and exhaust gas that have passed through the perforations of the partition must flow to reach said outlets, and in flowing through which the air and exhaust gas are intimately mixed and chemically combined and exhaust noise is muffled.
 3. a port for pressurized air in another wall, at a level below the partition; D. a baffle tube in the inlet compartment, extending lengthwise from one to the other of the side walls of the chamber and into which the gas inlet port opens, said baffle tube having an imperforate wall portion at the side thereof that faces the partition and having perforations in its other wall portions so that exhaust gas entering the chamber is discharged from the baffle tube in directions that encourage it to flow uniformly through all of the perforations of the partition; and E. a bed of particulate catalytic materiAl substantially filling the outlet compartment, of a type having the property of promoting the chemical combination of oxygen and pollution-causing products of incomplete combustion, the interstices between the catalytic particles providing a multitude of tortuous passages through which air and exhaust gas that have passed through the perforations of the partition must flow to reach said outlet ports, and in so doing become intimately mixed and chemically combined and acoustically muffled. 